The present invention generally relates to apparatus and methods for treatment of airstreams in an Environmental Control System (ECS) to remove particles using an aircraft electronic particle separation system.
ECS of various types and complexity are used in military and civil airplane, helicopter, and spacecraft applications. In aircraft for example, airflow may be circulated to occupied compartments, cargo compartments, and electronic equipment bays. Humid air containing many pollutants such as particulate matter, aerosols, and hydrocarbons may be delivered in a heated condition to the ECS. As the humid air cools, aqueous vapor condenses into liquid. The entrained moisture may be uncomfortable for passengers, unacceptable for air-cooled electronic equipment, may cause windshield fogging, and may cause corrosion to exposed metals. The ECS may include provisions to dehumidify the air supply during cooling operations to provide a comfortable environment for the passengers and crew, where particle separation may be an important function.
Some aircraft ECS operate on an air cycle refrigeration principle. Depending on the cycle architecture, particle separation may be categorized into high-pressure, mid-pressure, and low-pressure regimes. A high-pressure extractor typically removes the entrained moisture prior to expansion in the air cycle machine. A mid-pressure separation may be performed on air expanded by the high-pressure stage, but prior to expansion in the low-pressure stage in an air cycle machine with two cooling stages. A low-pressure separator typically removes the entrained moisture following expansion in the air cycle machine. In some separator systems, coalescence based separators may use filters to capture and agglomerate the small particles in airflow into larger droplets. Coalescence based separators typically have significant system pressure drops. The filters may also need frequent replacement requiring frequent maintenance on the system.
As can be seen, there may be an ongoing need to minimize system pressure drops and maintenance in ECS while maintaining liquid particle separation efficiency.